Cherry-pick #25590 to 7.13: Retry deamon reload during enroll

[michalpristas]

Cherry-pick of PR #25590 to 7.13 branch. Original message:

What does this PR do?

Adds retry for daemon reload

Why is it important?

elastic/fleet-server#297

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

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Pinging @elastic/agent (Team:Agent)

[elasticmachine]

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Build stats

• Build Cause: Pull request #25718 opened

• Start Time: 2021-05-14T09:14:50.293+0000

• Duration: 62 min 6 sec

• Commit: 68627d8

Test stats 🧪

Test	Results
Failed	0
Passed	6844
Skipped	24
Total	6868

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Test stats 🧪

Test	Results
Failed	0
Passed	6844
Skipped	24
Total	6868